Mechanical and thermal induced phase transformations in superduplex stainless steel

The aim of this work is to study the microstructural changes in SAF 2507 type superduplex stainless steel due to heat treatments and mechanical fatigue process. Specimens were heat treated in the 400-1360 °C temperature range for 1 and 5 hours respectively. An other series of specimens were periodically loaded by using a fatigue testing machine. The microstuctural changes were investigated by using a complex micromagnetic measuring system which includes a Barkhausen noise measuring and a magnetic harmonic analysing system. The RMS value of the Barkhausen noise, the distortion factor (k), and magnetic coercivity values were measured. The microstuctural changes were investigated by metallography using scanning electron microscope

An Observational Evidence for the Difference Between the Short and Long Gamma-Ray Bursts

The intrinsic fluence and duration distributions of gamma-ray bursts are well represented by log-normal distributions. This allows a bivariate log-normal distribution fit to be made to the BATSE short and long bursts separately. A statistically significant difference between the long and short groups is found. We argue that the effect is probably real. Applying the Cramér’s theorem these results lead to some predictions for models of long and short bursts

Anisotropy of the sky distribution of gamma-ray bursts

The isotropy of gamma-ray bursts collected in current BATSE catalog is studied. It is shown that the quadrupole term being proportional to \sim sin 2b sin l is non-zero with a probability of 99.9%. The occurrence of this anisotropy term is then confirmed by the binomial test even with the probability of 99.97 %. Hence, the sky distribution of all known gamma-ray bursts is anisotropic. It is also argued that this anisotropy cannot be caused exclusively by instrumental effects due to the nonuniform sky exposure of BATSE instrument. Separating the GRBs into short and long subclasses, it is shown that the short ones are distributed anisotropically, but the long ones seem to be distributed still isotropically. The character of anisotropy suggests that the cosmological origin of short GRBs further holds, and there is no evidence for their Galactical origin

Problems of Ferrite Content Determination

In this work five different methods – AC magnetometer, DC magnetometer, Feritscope, EBSD and X-ray diffraction - were compared with each other. These methods were used to determine the δ-ferrite content of samples. The limits, disadvantages and advantages of the applied methods were analyzed. The tested material was 2507 type super-duplex stainless steel. The samples were cold rolled and heat treated to modify their ferrite content

Magnetic saturation of poly(dimethyl-siloxane) matrix composites based magnetorheological elastomers

The most common used parameters in applications of magnetorheological elastomers are characteristic data of magnetization curve. Vibrating sample magnetometer (VSM) is a unique technique to record the magnetization curve of small samples. From measurement data the further calculations have to be done for determination of the saturation magnetisation as among other factors some materials can not be saturated with this VSM, but the saturation magnetization can be determine as the fitted curve´s parameter. It was found, that the saturation magnetisation depends on filling factor (as rate of components). To get composite saturation magnetisation components saturation magnetisation in proportion of their weight percentage should summing-up. The knowledge of error limits presents a usable tool for further examination

An intrinsic anisotropy in the angular distribution of gamma-ray bursts

The anisotropy of the sky distribution of 2025 gamma-ray bursts (GRBs) collected in Current BATSE catalog is confirmed. It is shown that the quadrupole term being proportional to similar to sin 2b sin I is non-zero with a probability 99.9%. The occurrence of this anisotropy term is then supported by the binomial test even with the probability 99.97%. It is also argued that this anisotropy cannot be caused exclusively by instrumental effects due to the non-uniform sky exposure of BATSE instrument; there should exist also some intrinsic anisotropy in the angular distribution of GRBs. Separating GRBs into short and long subclasses, it is shown that the 251 short ones are distributed anisotropically, but the 681 long ones seem to be distributed still isotropically. The 2-sample Kolmogorov Smirnov test shows that they are distributed differently with a 98.7% probability. The character of anisotropy suggests that the cosmological origin of short GRBs further holds, and there is no evidence for their Galactical origin. The work in essence contains the key ideas and results of a recently published paper (Balazs et al. 1998), to which the new result following from the 2-sample Kolmogorov-Smirnov test is added, too